(a) Field of the Invention
The present invention relates generally to a photosensitive resin composition, a thin film panel including a layer made with the photosensitive resin composition, and method of manufacturing the thin film panel. In particular, the invention relates to a photosensitive resin composition for insulation of a display panel.
(b) Description of Related Art
An active type display device such as an active matrix (AM) liquid crystal display (LCD) and an active matrix organic light emitting diode (OLED) display includes a plurality of pixels arranged in a matrix. The pixels in the matrix include switching elements, and the pixel boundaries are usually formed by a plurality of signal lines such as gate lines and data lines for transmitting signals to the switching elements. The switching elements of the pixels selectively transmit data signals from the data lines to the pixels in response to gate signals from the gate lines for displaying images. The pixels of the LCD adjust the transmittance of incident light according to the data signals, while those of the OLED display adjust the luminance of light emission according to the data signals.
The LCD and the OLED displays include a panel provided with the TFTs, the field-generating electrodes, the signal lines, etc. The panel has a layered structure that includes several conductive layers and insulating layers. The gate lines, the data lines, and the field-generating electrodes are formed of different conductive layers and separated by insulating layers.
The insulating layers are made of inorganic or organic insulators. Organic insulators have a transmittance higher than the inorganic insulators, and therefore often result in increased luminance (and an increased reference viewing angle for an LCD). Several of these organic insulators have a photosensitivity level that allows them to be patterned only by lithography without etching, thereby simplifying the display manufacturing process.
However, conventional photosensitive organic insulating layers often have spots or stains. In particular, as the display devices increase in size, slit coating or spin-and-slit coating is preferred to spin coating as a method of forming the organic insulating layers, and the slit coating and the spin-and-slit coating of the organic insulating layers frequently generate stains. The stains may be horizontal stains along a direction of a slit type nozzle of a coating device, vertical stains along a length direction of the slit type nozzle, and irregular spots over an entire surface of a substrate. In addition, portions of the organic layer near the edges of a substrate are sometimes thicker than other portions of the organic layer. These portions with extra thickness may not completely dissolve during the development such that they remain to form stains, degrading the image quality of the display device.
A method and device for forming organic insulating layers with fewer stains is desired.